Kmail and gnupg not playing nice

Hey all,
I configured kmail with my gnupg keys. I am able to send encrypted emails, and
am informed when emails arrive with a signature. The issue arrises when I
want to view and encrypted email.
I select the encrypted email and the preview pane shows a blue box with the
following error:
Encrypted message (decryption not possible)
Reason: Crypto plug-in "openpgp" could not decrypt the data.
Error: Bad
Encrypted data not shown.
End of encrypted message
Why am I only facing an issue when it comes to decrypting an email?
Thanks
Phil.